Soldering flux



Patented Oct. 15, 1940 UNITED STATES soLDEmNG raux Application February 23, 1939, Serial No. 257,851 10' Claims. (Cl. 148-23) This invention relates to soldering fluxes and to coredsolder made therewith, more particularly to soldering fluxes comprising naturally plastic materials and to cored solders employing such uxes.

Cored solders, that is, tubes of metallic solder filled with flux, suitable for many uses have .been known for a considerable length of time. Ordinarily such solders are lled with a flux consisting of rosin alone or of rosin mixed with some plasticizing agent, such as rosin oil, turpentine or the like. Such cored solders are a great convenience in ordinary soldering operations, the ux being thus carried with the solder directly to the part or point where a soldered connection is to be made. Also, such cored soldered strands have been used in electrical safety apparatus in which an excessive current beyond a predetermined value passing through such a strand will melt the strand and thus` break the circuit and prevent damage from electrical overloading.

When rosin alone is used as the core material it may be unsatisfactory for various purposes because of the brittle and friable nature of the rosin. If such rosin cored soldered strand is bent or crushed in any way, the core material at that point is powdered and may hence be unsatisfactory fors some purposes. Furthermore, the rosin is liable to come out of the end of the solder tube. For, this reason cored solders are made in which the rosin is plasticized with rosin oil, turpentine or the like. However, it is found that in some cases such cored solders when used under conditions of high temperature will become unsatisl factory because of the excessive softening or even .melting of the plasticized core.

. The objects of the present invention are to provide flux cored solders having cores of .material which are satisfactory both as to their mechanical characteristics and uxing properties and to provide new and improved soldering uxes.

In one embodiment of the present invention a tubular strand of solder is filled with a core made of gum or resinous -material which is naturally 4 and normally plastic under ordinary temperatures without involving the need for any foreign plasticizing ingredient. It has been found that suitablenatural gums or resins for this purpose are such gums as gum thus, gum elemi, and the naturally plastic forms of resins which are extracted from crude gutta perchas and balatas.

Other objects and features of the invention will appear from the following detailed description of one embodiment thereof taken in connection with the accompanying drawing, in which the temperatures and is an excellent flux for solderin crude gutta perchas and balatas and which PATENr oFFlca same reference numerals are applied to identical parts in the several gures and in which- Fig. 1 is an enlarged diagrammatic perspective view of a section of cored solder made in accordance with the present invention; and 5 Fig. 2 is a fragmentary sectional view of a portion of an extrusion press for manufacturing the product shown in Fig. 1. y

In the embodiment herein disclosed a strand l0 of cored solder comprises a metallic tube ll m of solder and a plastic core l2. The shell il is a tube preferably having a wall of uniform thickness and consisting of any suitable metal or metallic alloy, such as the various alloys of lead and tin commercially known as common solder or inl5 some instances of other metallic alloysvsuch as Woods metal, Roses metal, or the like. The core I2, preferably formed to fill the cylindrical bore of the body ll in accordance with the present invention, consists substantially entirely of a gum 20 or resin which is itself naturally plastic at ordinary temperatures, requiring no plasticizing agent to render it plastic.

One natural resin or gum which has been found to be eminently satisfactory both because it is 25 a suitable fiux for soldering operation and because it is naturally plastic at ordinary temperatures is the resin known as gum thusi a resinous exudation from the long-leaf pine tree, Pinus palustrz's, which grows in the southern United 30 States. This particular resin is scraped from the trees after the rst frost and differs from similar materials in that it is naturally plastic at ordinary temperatures.

Another suitable natural resin for this purpose 35 is that known as gum elemi, a natural resin obtained from a variety of sub-tropical or tropical plants, e. g., those knownI as Icz'ca icicarz'ba. Elaphrium elemiferum and Canarium commune. The resin which has been found to be most satis- 40 factory is the variety obtained principally from the Philippine Islands and sold under the name of Manila elemi. The gum elemi that is suitable for the purpose of this invention is characterized by being naturally or normally plastic at ordinary 45 ing operations.

A third type of material which has been found to be satisfactory comprises the plastic resins which occur as a natural admixture or impurity are extracted therefrom by means of suitable solvents, such as gasoline, naphtha, etc. One material of this nature, whiclrjs plastic at ordinary temperatures and acts as a soldering flux, is known commercially as G. P. resin.

One convenient method of making the product shown in Fig. 1 is illustrated by Fig. 2 of the drawing. This gure is a sectional view of a portion a pipe 45, which may be heated, if necessary, by

means of a llame 4l, and through channels -44 and 43, leading finally from the lower end of a nozzle 28 the outlet end of which is positioned within the entrance opening of an extrusion die 25. A solder 36, of any suitable composition, is contained in an extrusion cylinder 20v and while in a plastic state is forced by means of a ram 2| through the die 25. Thus the solder is caused to issue from the press as a tube I I enclosing the core I 2 of the plastic gum material, thereby forming the compound strand I0 consisting ofthe lshell or tube II of solder and the plastic core I2.

While the invention has been illustrated as embodied in a strand of cored solder consisting of a solder shell with a plastic gum core, the invention is not limited to the precise structure and ingredients shown. but is limited only by the appended claims. For example, the soldermay be in the form f hollow pellets of various shapes, which completely enclose the plastic core. Such pellets may be round, oblong or of any desired shape. Also, if desired, the tubular shell of the cored strand solder may be crimped at intervals in a manner well known in the art to provide a plurality of chambers enclosing batches of the plastic core. In addition, the shell in the strand form of the cored solder need not be in the form of a hollow circular cylinder, but may assume any desired form.

Furthermore, other naturally plastic gums or resins which have the property of acting as a. soldering flux may be substituted for those specically recited herein. Mixtures of these naturally plastic materials with each other or with other materials may likewise be used, ifA

desired, provided the mixtures used are plastic at ordinary temperatures. Obviously, these naturally plastic gums or resins need not be used solely as cores for cored solder but may be used in various forms for soldering operations in the same manner that rosin may be employed.

What is claimed ist i 1. A plastic soldering ux consisting essentially of material selected from the class consisting of gum thus, gum elemi and gutta percha and balata resins which is normally plastic at ordinary temperatures Without the admixture of any plasticizing agent.

2. A plastic soldering lx consisting essentially of gum thus which is normally plastic at ordinary temperatures without the admixture of any plasticizing agent 3. A plastic soldering flux consisting essentially of gum elemi which is normally plastic at ordinary temperatures without the admixture of any plasticizing agent.

4. A plastic soldering flux consisting essentially of G. P. resin which is normally plastic at ordinary temperatures Without the admixture of any plasticizing agent.

5. A plastic flux core for bodies of cored solder, consisting essentially of material of the class consisting of gums and resins which are normally plastic at ordinarytemperatures without the admixture of any plasticizing agent and which are capable of acting as soldering uxes.

6. A plastic ux core for bodies of cored solder, consisting essentially of material normally plastic -at ordinary temperatures without the admixture yof any plasticizing agent and selected from the class consisting of gum thus, gum elemi and gutta percha and balata resins.

7. A plastic ux core for bodies of cored solder, consisting essentially of gum thus which is normally plastic at ordinary temperatures without the admixture of any plasticizing agent.

8. A plastic flux core for bodies of cored solder, consisting essentially of gum elemi which is normally plastic at ordinary temperatures without the admixture of any plasticizing agent.

9. A plastic ux core for bodies of cored solder, consisting essentially of G. P. resin which is normally plastic at ordinary temperatures Without the admixture of any plasticizing agent.

10. A plastic soldering flux constisting essentially of material normally plastic at ordinary temperatures without the admixture of any plasticizing agent and selected from the class consisting of gums and resins normally plastic at ordinary temperatures without the admixture of any plasticizing agent and which are capable of acting as soldering'uxes.

WILLIAM A. sornzUcH.rr` 

